Road binder



Patented Mar. 13, 1928.

UNITED sures PATENT orica.

MICHAEL H. 'COUGHLIN, OF STOUGH'I'ON, MASSACHUSETTS.

ROAD BINDER.

Ho Drawing.

ing qualities of bituminous substances such as asphalt, coal tar and wax tailings.

In practising my invention, I use as one element, a bitumen which is preferably but not necessarily rendered basic by the addition, if necessary, of an alkali. Coal tar may be used for this purpose and does not require the addition of any alkaline 'substance. If liquid asphalt is used, this being acid in its natural state, I add caustic soda, calcium hydroxide or ammonia in the proportion of from 2% to 5 per cent.' Wax tailings may be used in place of asphalt or coal tar but requires to-be neutralized by the use of alkali. It Will be understood of course that mixtures of various bitumens may be employed, suflicient alkali being employed to render the whole somewhat alkaline in reaction.

The bitumen, after being rendered alkaline if necessary, is mixedwith a. solution which is made as follows :-I take sulphite liquor of approximately 30 Baum or a liquid made by dissolving eight (8.) pounds of sulphite powder in one ('1) gallon of water which gives a practically equivalent solution, and to this I add an'organic acid as, for instance, lactic or acetic acid, using from four (4). to eight (8) ounces of aci for each gallonof sulphite liquor. In the case of either acid, the strength is -44= Baum.

The alkaline bitumen is then mixed with Application filed February 24, 1922. Serial No. 539,032.

The acid employed has the effect of reducmg the viscosity of .the final product, whether tar, asphalt or wax tailings be used as a base, so that it distributes" itself through the gravel, stone or sand with which it is used, more readily and permeates much more quickly than the, ordinary bitumens alone. I also find that it affords morebond and, when-incorporated with aggregates, setsmore firmly.

The sulphite liquor increases the bond and, being extremely hygroscopic, pievents the volatilization of the bitumen, thus acting as a preservative, greatly increasing the life of the bitumen. The acetate of lime or lactic tannate, which are believed to be formed, also-prevent the oil in the tar or asphalt from being volatilized and in some way cause the sulphite liquor to amalgamate with the bitumen.

I find that when mingled with a proper proportion of suitable aggregates such as fine gravel, sand or broken stone, the composition may be laid cold, and when so laid, will set satisfactorily and have excellent wearing qualities due chiefly, I believe, to the factthat the oils contained in the bitumen do not volatilize readily owing to the presence of the reaction products of the acids employed. Organic acid as used in the appended claims includes any capable of performing those functions outlined to provide a satisfactory final product of the type described.

What I claim is '1. The road inder which comprises a basic bituminous substance, sulphite liquor, and lactic acid.

2. The road binder which comprises five parts of'(a) asphalt and lime 2 to 5 per cent of the asphalt and (b) one part of sulphite liquor of about 30 Baum to which has been added lactic acid in the proportion of four to eight ounces of acid to each gallon of the sulphite liquor.

the sulphite liquor and acid at the ratio oh In testimony whereof I aflix my signature.

five (5) parts of bitumen to one (1) of sulphite liquor and the whole thoroughly stirred to render it-homogeneous.

MICHAEL F. CQUGHLIN; 

